Method of treating materials



May 13, 1941. B. A. SMITH 2,241,429

METHOD OF TREATING MATERIALS Filed Aug. 14, 1937 2 Sheets-Sheet 1ATTORNEY6 May 13, 1941. B. A. SMITH METHOD OF TREATING MATERIALS FiledAug. 14, 1937 2 Sheets-Sheet 2 IIIIIIIIII/ INVENTOR. flea/am! 4.5m c90&1

Patented May 13, 1941 METHOD OF TREATING NIATERIALS Benjamin A. Smith,Lakewood, Ohio, assignor to The C. 0. Bartlett & Snow Company,Cleveland, Ohio, a corporation of Ohio Application August 14, 1937,Serial No. 159,140

.2 Claims.

This invention relates, as indicated, to an improved method of thetreatment of materials, and this invention particularly relates to amethod of the preparation of charges of raw material prior to theirintroduction into conventional furnaces, usually of the electric type,employed in the manufacture of metallic alloys.

The manufacture, or more particularly, the smelting of metallic alloys,usually accomplished by a reduction of the ore and frequently thesmelting therewith of a certain amount of scrap metal, is generallycarried on in an electric furnace for the reasons well known in the art.While it is usually necessary and desirable to carry on the finalsmelting operation under the carefully controlled conditions possible inan electric furnace, it is generally not necessary nor economical toheat the material from its cold state in the electric furnace. If theingredients or constituents of the final charge can be heated properlyup to a temperature below which the carefully controlled conditionsexisting in the electric furnace are not necessary, then more economicalmeans such as hydrocarbon fuels may be employed to effect such initialheating with a consequent saving in total cost.

It is the principal object of my invention to provide a method by whichthe above-referred to preliminary heating of the charge constituents maybe advantageously and economically effected.

It is a further object of my invention to provide a method of thecharacter described characterized by the fact that the preliminaryheating of the raw materials is effected in a most economical manner andin such a way as to insure that the charges supplied to the electricfurnace for the final heating, reduction or smelting operation may beuniform as to quantity and quality so as to insure maximum efii ciencyof operation of the electric furnace and uniformity of the productproduced thereby.

Other objects of my invention will appear as the description proceeds.

I To the accomplishment of the foregoing and related ends, saidinvention, then, consists of the means hereinafter fully described andparticularly pointed out in the claims; the annexed drawings and thefollowing description setting forth in detail certain means and one modeillustrating, however, but one of the various ways in which theprinciple of the invention may be used.

In said annexed drawings:

Fig. 1 is a plan view showing somewhat diagrammatically one form ofapparatus capable of carrying out the principles of my invention.

Fig. 2 is a side elevational View, partially in section, of one of theunits which comprise the combination illustrated in Fig. 1.

Fig. 3 is a transverse sectional view drawn to an enlarged scale of aportion of the apparatus illustrated in Fig. 1 taken on a planesubstantially indicated by the line 3-3.

Fig. 4 is a transverse sectional View of a portion of the structureillustrated in Fig. 3, taken on a plane substantially indicated by theline 44; and

Fig. 5 is a fragmentary sectional view of a portionof the apparatusillustrated in Fig. 3, taken on a plane substantially indicated by theline Broadly stated, this invention comprises a method of thepreliminary heating of charges of raw material such as may be introducedinto an electric metallurgical furnace characterized in that separateheating kilns are employed for such constituents as it is convenient ordesirable to preliminarily heat separately before introduction into thesmelting furnace. Such kilns are preferably sufiiciently large incapacity to accommodate a quantity of impounded raw materialsubstantially greater, and for most purposes several times the quantityof, individual charges of the particularly impounded material.

The impounded material may be heated by some relatively inexpensivehydrocarbon fuel and at a substantially uniform rate so that when theimpounded material, as it is depleted for the purpose of charging thesmelting furnace, is replenished at such a rate as to maintainsubstantially constant the temperature of the kiln within which thepreliminary heating is effected.

Referring now more specifically to the drawings and more especially toFig. 1, the arrangement here illustrated is a plan view of aconventional installation constructed in accordance with the principlesof my invention. The electric furnace or similar smelting furnace,generally indicated at I is of course the smelter or melting devicewhich is to be supplied with charges of raw material by the process andapparatus of my invention. The numeral 2 denotes the location of a cranecab, such crane operating, for example, along the line generallyindicated at 3, being capable of readily transporting the raw materialconstituents comprising the charge which may be introduced, for example,centrally to the smelter I. Positioned in suitably spaced relation withrespect to each other and desirably arranged with respect to the line 3of movement of the crane for the purposes hereinafter more fullyexplained are a plurality of kilns generally indicated at 4 and 5respectively. The number of separate kilns employed in a particularinstallation will depend, of course, upon the nature of the raw materialwhich is being smelted. For purposes of illustration, only two of suchkilns have been shown since the principles of my invention apply withoutsubstantial modification to an arrangement comprising greater number ofsuch kilns. Throughout the ensuing description it will be assumed,therefore, for the purpose of simplifying this description that thecharge to be supplied to the furnace i will consist of two primaryconstituents, for convenience referred to as the ore and lime. It isassumed, therefore, for purposes of illustration in describingtheinvention, that the furnace l is a reduction furnace to be supplied withcharges consisting of pre-determined amounts of ore and lime. For themanufacture of more complex metal alloys it may, of course, bedesirable, as above pointed out, to maintain as separate units a greaternumber of the charge constituents requiring the use of a correspondinglygreater number of separate kilns.

It is likewise within the contemplation of my invention to employ asingle pre-heating kiln into which may be introduced a mixture of all ofthe ingredients and in the proper proportions required for the charge tothe smelter. This may be necessary and desirable where the nature of thecharging materials is such that they may be advantageously or desirablypre-heated while 7 character. Each kiln will be provided with an annulardriving gear 9 which will be in mesh with a driving pinion and itsassociated speed reduction mechanism and driving 'motor, not shown.These last-named elements have been omitted from the illustration inorder to clarify the drawing. It will be noted, however, that thedriving means for the kilns 6 will be capable of selectively drivingeach kiln in opposite :directions.

Each kiln may be provided with a feed hopper Ill containing the coldrawmaterial which may be fed thereto by any suitable means such as ascrew conveyor, generally indicated at H. The hopper H1 may, of course,be supplied with raw material from a bin, generally indicated at 42, andbuckets or cars such as 13 may, of-course, be employed for the purposeof conveying the raw material from the bin to the hopper. It is, ofcourse, within the contemplation of my invention to variously arrangethe supply of raw material so as to maintain in the hopper Iii anadequate quantity of the same to be fed into the kiln 8 by the feedingdevice N. If desired, the'feeding device II and its associated hopperill may be moved on a platform Hi which, mounted on rollers,'rnay bemoved to and from the feeding opening in the kiln B. This arrangementpermits ready inspection and repair of the various work ing parts, andif desired, the feeding device, genkiln 6 supplied with the necessaryquantity of impounded material to be heated in preparation for thecharge. In such case the opening through which the material is fed tothe kiln 6 may be closed by some removable device which would assist inconserving the heat within the kiln 6.

At the opposite end of the kiln 6 from the feeding device H is ahydrocarbon fuel burner generally indicated at I5 and it is within thecontemplation of my invention to employ any suitable fuel in suchburner, such as, for example, gas, oil or powdered coal. This burnerheats the material internally or directly.

The stack opening from the kiln 6 will preferably be in the same endwith the feeding opening, for example, the stack opening may beconcentric with the feeding opening, in which case the duct or flue l6may extend downwardly and lead to the main stack for the plant.

Each kiln 6 will be, at some convenient location preferably adjacent theend occupied by the hydrocarbon burner, provided with a discharge ring,generally indicated at H, the construction and mode of operation ofwhich may be more readily determined by having reference to Figs. 3 to5.

Referring now to Fig. 3, the outer periphery of the kiln 6 is indicatedby the line I8. Within the outer shell the kiln is of course providedwith a refractory lining which extends inwardly to the line I9. Arrangedin a circumferentially extending groove on the inner periphery of thisrefractory lining are a plurality of complementary segmental members,generally indicated at 2B.

erally indicated at H, maybe movedinto'feed;

tervalsi as'it is necessary inorder'to'keep the ingre'lation with thekiln 6. during only su'ch ina These segmental members will be of somesuitable high-temperature-resistant alloy and substantially rectangularin shape, each providing a short circumferentially extending laterallyrestricted passage for the flow of material from the interior of thekiln to the outside thereof. One end of each of these segmental units 20is provided on its inner face with an opening 2! and the opposite endsof these segmental units are respectively provided with outwardlyextending throats 22. Th several segmental units are provided withcircumferentially extending fingers 23 which, when the several units areassembled in themanner illustrated in Fig. 3 and at their outer endsbolted to the shell of the kiln 6, will look all of these segmentalunits against displacement. The casing 24 around the kiln 6 in thecircumferential area occupied by the segmental units 26 is for thepurpose of collecting the material discharged from the kiln, and asuitable spout such as 25 may be provided to carry the dischargedmaterial into a car or bucket 26 which will'be supported for convenienceon a weighing scale platform 21 by which the quantity. of materialdischarged for a particular charge may be accurately determined.

It will be observed that when the kiln rotates in the directionindicated by the arrow 28 in Fig. 3 the Y material within the kiln willbe scooped up through the openings 2| by the segmental members Zfl andas each segmental member moves to the lowermost position the contents ofthe passage through such member will be dis charged into the spout 25.If, however, the kiln is rotated in a direction opposite to that of thearrow 28 the material will be prevented from flowing out through thesegmental membersand the material which has fallen into the openings 2iwill substantially seal the ,same and thus con iefve. the heat andburning gases within the In the operation of the apparatuses abovedescribed in carrying out the principles of my invention, the ore andlime, for example, shall go to make up the component parts of the chargefor the furnace which will be introduced into the respective kilns 4 and5. A sufficient quantity of raw material will be maintained in each kilnat all times so as to more than supply the requirements for a singlecharge for the furnace I. In fact, it will be found desirable in certaininstances to impound enough material in each kiln to supply therequirements of several individual charges. Thus, a residual charge ofhot material is left in each kiln at all times. When heated material iswanted for the furnace charge the kiln, normally rotated in such adirection as to retain the material therein and to agitate the same soas to insure its being uniformly heated, will be stopped and rotated inthe opposite direction. This will result in a discharge of the heatedmaterial from the kiln so reversed, and the discharged material willflow into the car 26 where it can be weighed and the rotation of thekiln in the discharging direction stopped when the desired amount ofmaterial has been withdrawn. The car 26 will preferably be refractorylined, covered and thermally insulated to preserve the heat of thematerial therein during the time when the car is transferred by means ofthe crane or otherwise over to the furnace and its contents charged intothe furnace. It will be observed that the discharge point in the kiln issubstantially removed from the charging point, and if a sufiicientquantity of raw material is impounded in the kiln it may be entirelyfeasible to feed the raw material into the kiln at a continuous uniformrate. Thus it is feasible for certain types of material, and where theimpounded quantity of raw material is great enough, to continue thefeeding of the cold material into the kiln simultaneously with theWithdrawal of hot material therefrom. For certain types of material itmay be found desirable to interrupt the feeding of cold material intothe kiln for an interval shortly prior to the time when a charge is tobe withdrawn from the kiln.

It will be observed from the foregoing description that I have provideda method of and ap para-tus for preliminarily heating the charges formetallurgical furnaces characterized by the fact that this preliminaryheating of the raw material may be carried on in a substantiallycontinuous manner so as to utilize to the fullest extent the heat of thepreliminary heating medium. Furthermore this process insures thenecessary supply at all times of the components of the charge for thefurnace and at uniform conditions particularly with respect totemperature; the preliminary heating being accomplished by the use ofrelatively inexpensive fuel, the process comprising my inventionmaterially reduces the total cost of the smelting operation.

It is further frequently found desirable to accomplish the preliminaryheating in an oxidizing atmosphere to the end that free carbonaceousmaterials contained in the ingredients entering into the furnace charge,may be fully oxidized and converted to gases which pass out of thepreheater apparatus thereby greatly assisting the control of carbon inthe alloy subsequently produced by the furnace.

Other modes of applying the principle of my invention may be employedinstead of the one explained, change being made as regards the means andthe steps herein disclosed, provided those stated by any of thefollowing claims or their equivalent be employed.

I, therefore, particularly point out and distinctly claim as myinvention:

1. The method of charging a metallurgical furnace for metal alloymanufacture which comprises separately impounding the reducing andreducible materials in quantities substantially greater than thatrequired for individual charges, heating internally such impoundedmasses at substantially constant rates while continuously agitating thesame, intermittently withdrawing from such impounded masses suflicientof such pre-heated material to constitute a charge for the furnace whilecontinuing the agitation of said mass and replenishing the impoundedmass so intermittently depleted by the addition thereto of raw materialat such a rate that the temperature of the impounded mass is notsubstantially changed by the introduction of such raw material.

2. The method of charging a metallurgical furnace for metal alloymanufacture which comprises impounding a charge material in quantitiessubstantially greater than that required for individual charges, heatinginternally such impounded mass at substantially constant rates whilecontinuously agitating the same, intermittently withdrawing from suchimpounded mass sufiicient of such preheated material as is required fora charge for the furnace while continuing the agitation of said mass andreplenishing the impounded mass so intermittently depleted by theaddition thereto of raw material at such a rate that the temperature ofthe impounded mass is not substantially changed by the introduction ofsuch raw material.

BENJAMIN A. SMITH.

